pipe()函數 Unix/Linux
內容簡介
#include <unistd.h>int pipe(int filedes[2]);
描述
pipe() creates a pair of file descriptors, yiibaiing to a pipe inode, and places them in the array yiibaied to by filedes. filedes[0] is for reading, filedes[1] is for writing.返回值
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.錯誤
| 標簽 | 描述 |
|---|---|
| EFAULT | filedes is not valid. |
| EMFILE | Too many file descriptors are in use by the process. |
| ENFILE | The system limit on the total number of open files has been reached. |
遵循於
POSIX.1-2001.實例
The following program creates a pipe, and then fork(2)s to create a child process. After the fork(2), each process closes the descriptors that it doesn’t need for the pipe (seepipe(7)). The parent then writes the string contained in the program’s command-line argument to the pipe, and the child reads this string a byte at a time from the pipe and echoes it on standard output.#include <sys/wait.h> #include <assert.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> int main(int argc, char *argv[]) { int pfd[2]; pid_t cpid; char buf; assert(argc == 2); if (pipe(pfd) == -1) { perror("pipe"); exit(EXIT_FAILURE); } cpid = fork(); if (cpid == -1) { perror("fork"); exit(EXIT_FAILURE); } if (cpid == 0) { /* Child reads from pipe */ close(pfd[1]); /* Close unused write end */ while (read(pfd[0], &buf, 1) > 0) write(STDOUT_FILENO, &buf, 1); write(STDOUT_FILENO, " ", 1); close(pfd[0]); _exit(EXIT_SUCCESS); } else { /* Parent writes argv[1] to pipe */ close(pfd[0]); /* Close unused read end */ write(pfd[1], argv[1], strlen(argv[1])); close(pfd[1]); /* Reader will see EOF */ wait(NULL); /* Wait for child */ exit(EXIT_SUCCESS); } }
